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采用了新的"酸酐法"使用2,2-二羟甲基丙酸(DMPA)来合成一种具有规整结构树枝状大分子.制备好的树枝状大分子通过高效酯化反应接枝到聚乙二醇(PEG)两端,形成结构高度支化、表面官能团密度大、单分散性的大分子.树枝状大分子的制备过程中的分步提纯进行彻底,反应物在高效催化剂(DMAP)的存在下反应活性大,反应完全,得到的产物极其规整.之后用一步合成方法得到了树枝状大分子-聚乙二醇-树枝状大分子(dendrimers-PEG-dendrimers)的聚合物.通过红外光谱(FTIR)、核磁共振氢谱(1H-NMR)、凝胶渗透色谱(GPC)对聚合物及其中间产物的表征表明,合成的高分子结构严密地与理论相吻合. 相似文献
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应用不同烧结温度制备VC颗粒增强铁基复合材料,用扫描电镜(SEM)观察各烧结温度下的微观结构,应用该组分做差热分析(DTA)、高温X射线衍射分析(XRD)对Fe-V-C体系原位合成VC的动力学过程进行研究,该动力学研究将为VC/Fe复合材料制备提供了理论依据。结果表明,在700℃时左右σ相(Fe V)在石墨的作用下发生分解,变成固溶了大量钒的α-Fe,随着温度的升高,V与C发生反应生成VC;温度越高,VC发生反应越激烈,并释放出大量的热量;1 100℃真空烧结后的组织为珠光体基体上分布着大小均匀呈球形的VC颗粒。 相似文献
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采用红外光谱(FT-IR)技术研究了新型位阻型酰胺扩链剂二乙酰乙二胺(MEDA)和二乙酰己二胺(MHAD)与4,4′-二苯甲烷二异氰酸酯(MDI)的扩链反应。考察了酰胺扩链剂对聚脲凝胶时间的影响,得出酰胺扩链剂能大大延长聚脲的凝胶时间,有利于反应动力学分析。扩链反应动力学研究结果表明,脂肪族酰胺扩链剂合成聚脲的扩链反应中,在反应初期低转化率时,反应均遵循二级动力学关系,得出MEDA和MHAD合成聚脲反应的活化能Ea分别为36.81 kJ/mol和43.99kJ/mol;MEDA反应活性高于MHAD. 相似文献
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以4,4'-(1-苯乙基)双酚(双酚AP)、正辛胺和甲醛为原料,采用溶剂法合成了一种新型双酚AP基苯并噁嗪单体,利用FT-IR和1H NMR对产物结构进行了表征,采用差式扫描量热仪(DSC)研究了苯并噁嗪单体的等温固化反应动力学.结果表明,该树脂体系的固化反应在反应前期为化学动力学控制,后期变为扩散控制占主导地位的反应,苯并噁嗪的固化过程为自催化和扩散控制.在反应后期实验数据和理论数据出现了偏差,通过将扩散因子引入到自催化模型中,改进后的自催化模型与实验数据相符. 相似文献
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PS/PBA/P(BA-AA)胶乳型互穿网络聚合物的合成及其反应过程表观动力学的研究 总被引:1,自引:0,他引:1
采用种子乳液聚合技术,合成了PS\PBA\P(BA-AA)胶乳型互穿网络聚合物,利用质量分析法研究了反应过程的表观动力学,测得了三步反应的聚合动力学曲线,探讨了初始乳化剂浓度、引发剂浓度对各步反应速率的影响。结果表明,以二乙烯基苯为交联剂,苯乙烯乳液聚合反应速率R∝[E][I];在交联PS种子乳液存在下,以EGDM为交联剂,丙烯酸丁酯乳液聚合的反应的动力学曲线与经典乳液聚合有所差异。透射电镜观察表明合成的聚合物具有明显的核-壳结构,且粒径均匀。 相似文献
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化学动力学疗法(CDT)是基于磁铁矿纳米酶治疗癌症的新兴治疗方式.但是,它的低催化能力和单模治疗限制了其治疗功效.本工作中,我们开发了一种在第二近红外(NIR-Ⅱ)窗口中具有高吸光度的碳涂覆的磁铁矿纳米团簇(CCMNCs),用于NIR-Ⅱ光热增强的化学动力抗癌疗法.这种尺寸约58 nm的CCMNCs通过使用二茂铁作为单一前体的一步溶剂热法合成.CCMNCs不仅用作肿瘤靶向磁共振成像的造影剂,而且还吸收并将NIR-Ⅱ辐射转化为局部热量,用于高温杀死癌细胞.CCMNCs在酸溶液中产生的亚铁离子和铁离子催化Fenton反应生成CDT的羟基自由基(·OH),并减少作为自由基清除剂的细胞内谷胱甘肽.本文报道的CCMNCs通过组合的化学动力学光热处理的协同效应显示出优异的治疗功效. 相似文献
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粉状乳化炸药热分解动力学研究 总被引:2,自引:0,他引:2
利用热重法(TG)研究了粉状乳化炸药的热分解过程和非等温反应动力学,采用Ozawa法和非线性等转化率积分法获得了其热分解动力学参数和机理函数。结果表明,粉状乳化炸药初始分解温度稍高于乳化炸药基质,分解活化能为97kJ/mool,是热稳定性良好的工业炸药。粉状乳化炸药的热分解机理属随机成核和随后成长,热分解动力学方程为dα/dt=1×10^10×(1-α)exp(-1.2×10^4/T)。 相似文献
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Goethite (alpha-FeOOH), one of soil contents, can be dissolved in acidic water to produce ferrous ions initiating Fenton reaction with hydrogen peroxide to degrade explosive. In this study, a series of catalytic degradation of nitro aromatic explosives, namely picric acid (PA) and ammonium picrate (AP) have been investigated using the FeOOH/H2O2 process. The controlling factors, such as adsorption of goethite dosage, hydrogen peroxide concentration and UV-light exposure on the oxidation of nitro aromatic explosives were investigated. The results showed that target compounds were adsorbed on the surface of goethite while the oxidation was proceeding. Furthermore, inhibition effect of nitro aromatic intermediates on the reaction was also discussed. A half-life kinetic model has been proposed to predict the half-lives of explosive oxidation in the goethite/H2O2 system. 相似文献
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采用加速度量热法评价工业炸药热安全性的研究 总被引:8,自引:1,他引:7
文章介绍了一种新的测试工业炸药热安全性的方法-加速度量热法(ARC),并用此法对BDS型安全乳化炸药和普通1116型乳化炸的热分解特性进行了测试研究,得到了两种炸药及其与硫化矿反应的有关热分解动力学数据,由此判断炸药在硫化矿中使用的安全性。 相似文献
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Greish YE Bender JD Lakshmi S Brown PW Allcock HR Laurencin CT 《Journal of materials science. Materials in medicine》2005,16(7):613-620
The low temperature synthesis of composites potentially suitable as bone substitutes which form in vivo, was investigated. The composites were comprised of stoichiometric hydroxyapatite (SHAp) and water-soluble poly phosphazenes. These constituents were selected because of their biocompatibility, and were mixed as powders with a phosphate buffer solution (PBS) to form the composites. The effects of poly[bis(sodium carboxylatophenoxy)phosphazene] (Na-PCPP) or poly[bis(potassium carboxylatophenoxy) phosphazene] (K-PCPP) on stoichiometric hydroxyapatite (SHAp) formation from tetracalcium phosphate and anhydrous dicalcium phosphate were assessed. The kinetics and reaction chemistries of composite formation were followed by isothermal calorimetry, X-ray diffraction, infrared spectroscopy and scanning electron microscopy. In the presence of 1% by weight of polyphosphazenes, composites comprised of SHAp and calcium cross-linked polymer salts were formed. Thus a mechanism for binding between polymer chains was established. Elevated proportions (5 and 10% by weight) of polyphosphazene, however, resulted in the inhibition of SHAp formation. This is attributed to the formation of viscous polymer solution coatings on the calcium phosphate precursors, retarding their reaction, and consequently inhibiting SHAp formation. 相似文献
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Laszlo J. Kecskes 《Materials and Manufacturing Processes》1999,14(1):123-145
A novel hot explosive compaction (HEC) technique has been applied to molybdenum (Mo) and tungsten (W)-based titanium (Ti) alloys. The precursor powders of the alloy billet were surrounded by an exothermic mixture, which, when ignited, released a large amount of heat via a self-propagating high-temperature synthesis (SHS) reaction. Heat from the SHS reaction diffused into the precursor powder bed, causing the interior temperature to rise above 1,500°C. When the powder bed became isothermal, it was consolidated to high density by pressure waves generated by the detonation of an explosive. The amount of explosive charge and the molar ratio of exothermic mixture to sample were adjusted to produce full-density Mo-Ti and W-Ti alloys. The billets were sectioned and examined with scanning electron microscopy (SEM), energy dispersive x-ray spectroscopy (EDS), x-ray diffraction analysis (XRD), and microhardness measurements. In context of the fabrication process the similarities and differences of the resultant product microstructures are discussed. 相似文献